The other night, we had our fourth session, counting the introduction session where the DM introduced us all. (All of the players are from different campaigns he ran in the past. I'd like to think this is a greatest hits campaign :D) And that session is where things really clicked.
Clicked as far as the game is concerned. As far as everyone getting along and having fun, we had that down from day one. But the first couple sessions were basically spent trying to get to grips with the Roll20 interface and each one was basically a minor combat apiece.
Session number four, we finally had a working knowledge of how to use the interface. We also started to do the basic D&D 101 experience, a dungeon crawl. The familiarity and simplicity of that helped us move things along. And the characters' personalities started to come out.
I now know the core concept of my fighter's personality, which is sacrifice. He is always first in battle and will do his best to define the front but not for glory or valor. His whole schtick is to protect everyone else, no matter the cost. Now that that has solidified as a motivation, I know what to do in any given situation. And I think everyone else is in a similar position.
Campaign are fragile creatures. They can break or fizzle out so easily. But now, we have a sense of ourselves as a group, which is a big step.